General control non-repressed 2 (GCN2) is a ser/thr kinase that alters translation in response to various cellular stresses. Recently we published data suggesting that GCN2 is activated in response to apoptotic cell challenge in splenic dendritic cells and macrophages controlling cytokine production, thus suggesting a novel mechanism of tolerance induction dependent on GCN2. In this proposal we will examine how GCN2 influences phagocyte responses to apoptotic cells using mice with a complete or cell specific defects in GCN2 function testing the role of GCN2 and its downstream effector C/EBP homologous protein 10 (CHOP) in apoptotic cell induced cytokine production, phagocyte maturation, antigen presentation to T cells, and ability to suppress adaptive T cell responses and induce long-term tolerance in a skin allograft model. Moreover we will examine the impact of GCN2 disruption on development of lupus in mouse models and will test the ability of the GCN2 activating drug, halofuginone, to inhibit autoimmunity development and disease pathology in animal models of the disease. Thus, the project will provide key mechanistic rationale to explore GCN2 pathway manipulation as a therapeutic target in lupus and other autoimmune diseases. !